U.S. patent number 8,771,501 [Application Number 12/989,278] was granted by the patent office on 2014-07-08 for elimination of chlorine compounds from hydrocarbon cuts.
This patent grant is currently assigned to IFP Energies Nouvelles. The grantee listed for this patent is Jean Cosyns, Quentin Debuisschert, Olivier Ducreux, Fabienne Le Peltier. Invention is credited to Jean Cosyns, Quentin Debuisschert, Olivier Ducreux, Fabienne Le Peltier.
United States Patent |
8,771,501 |
Cosyns , et al. |
July 8, 2014 |
Elimination of chlorine compounds from hydrocarbon cuts
Abstract
The invention concerns a process for purification by elimination
of chlorine in the form of hydrogen chloride and organochlorine
compounds by contacting in the presence of hydrogen of at least a
part of the effluent from a reforming, aromatics production,
dehydrogenation, isomerisation or hydrogenation zone, said part of
the effluent comprising olefins, hydrogen chloride and
organochlorine compounds, on an elimination zone comprising a chain
arrangement of two masses, the first mass being a mass comprising
at least one metal from group VIII deposited on a mineral carrier
and the second mass being a hydrogen chloride adsorbent.
Inventors: |
Cosyns; Jean (Maule,
FR), Ducreux; Olivier (Louveciennes, FR),
Debuisschert; Quentin (Rueil Malmaison, FR), Le
Peltier; Fabienne (Rueil Malmaison, FR) |
Applicant: |
Name |
City |
State |
Country |
Type |
Cosyns; Jean
Ducreux; Olivier
Debuisschert; Quentin
Le Peltier; Fabienne |
Maule
Louveciennes
Rueil Malmaison
Rueil Malmaison |
N/A
N/A
N/A
N/A |
FR
FR
FR
FR |
|
|
Assignee: |
IFP Energies Nouvelles
(Rueil-Malmaison Cedex, FR)
|
Family
ID: |
40021945 |
Appl.
No.: |
12/989,278 |
Filed: |
March 27, 2009 |
PCT
Filed: |
March 27, 2009 |
PCT No.: |
PCT/FR2009/000337 |
371(c)(1),(2),(4) Date: |
October 22, 2010 |
PCT
Pub. No.: |
WO2009/133260 |
PCT
Pub. Date: |
November 05, 2009 |
Prior Publication Data
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|
|
Document
Identifier |
Publication Date |
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US 20110040136 A1 |
Feb 17, 2011 |
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Foreign Application Priority Data
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Apr 25, 2008 [FR] |
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08 02345 |
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Current U.S.
Class: |
208/262.1;
208/99 |
Current CPC
Class: |
B01D
53/75 (20130101); C10G 69/08 (20130101); C10G
45/04 (20130101); C10G 45/10 (20130101); B01D
53/04 (20130101); B01D 53/8662 (20130101); C10G
25/003 (20130101); C10G 35/04 (20130101); B01D
2255/1023 (20130101); B01D 2255/202 (20130101); B01D
2255/204 (20130101); C10G 2300/201 (20130101); B01D
2257/2045 (20130101); B01D 2253/104 (20130101); B01D
2255/1021 (20130101); B01D 2257/2064 (20130101) |
Current International
Class: |
C10G
45/04 (20060101); C10G 69/08 (20060101) |
Field of
Search: |
;208/99,262.1 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0948995 |
|
Oct 1999 |
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EP |
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1053053 |
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Nov 2000 |
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EP |
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Other References
World IP Organization. "International Search Report and Written
Opinion." PCT/FR2009/000337, Examiner: Julien Hart, Applicant: IFP,
Mailed Sep. 3, 2009. cited by applicant .
Espacenet Database: "English Abstract--Process for removing
halogenated compounds from a gas or liquid with at least one
metallic element-containing composition." EP0948995, Applicant:
IFP, Oct. 13, 1999. cited by applicant.
|
Primary Examiner: Boyer; Randy
Assistant Examiner: Doyle; Brandi M
Attorney, Agent or Firm: Millen, White, Zelano &
Branigan, P.C.
Claims
The invention claimed is:
1. A process for purification of at least a part of an effluent
from a reforming zone said effluent comprising olefins, hydrogen
chloride and organochlorine compounds by elimination of chlorine in
the form of hydrogen chloride and organochlorine compounds, said
process comprising contacting in the presence of hydrogen a part of
the effluent in an elimination zone comprising a serial arrangement
of two masses, the first mass being a mass comprising palladium
impregnated on a mineral carrier and the second mass being a
hydrogen chloride adsorbent, wherein said mineral carrier of said
first mass consists of balls or cylindrical extrudates which
consist of alumina and said palladium is present on said carrier at
essentially only in a skin thickness of generally between 100 and
700 microns representing not more than 80% of the radius of said
beads or extrudates.
2. A process for purification by elimination of chlorine according
to claim 1 wherein at least a part of the effluent from the
reforming zone circulates through a gas-liquid separator, said
separator leading to a flow of gas rich in hydrogen (A) and a
liquid effluent (B), said liquid effluent being passed to a
stabilisation zone, said stabilisation zone providing at least two
cuts, a first light cut (C) and a first heavy cut (D), said first
heavy cut being passed to a fractionating column leading to the
production of at least two cuts, a second light cut (E1) taken off
at the column head, which cut (E1) can be passed to a benzene
hydrogenation zone, and a second heavy cut (F), a purification zone
integrated with any flow coming from the gas-liquid separator, a
stabilisation column or the fractionating column.
3. A process for purification by elimination of chlorine according
to claim 2 wherein said fractionating column leads to the
production of at least three cuts, a second light cut (E1) taken
off at the column head, a cut (E2) taken off between the column
head and the supply of the column, each of which cuts (E1) and (E2)
can be passed to a benzene hydrogenation zone, and a second heavy
cut (F).
4. A process for purification by elimination of chlorine according
to claim 3 wherein the purification zone is integrated with the
flow of gas which is rich in hydrogen (A), the liquid effluent (B)
or at least one of the cuts (E1) or (E2).
5. A process for purification by elimination of chlorine according
to claim 1 wherein the elimination zone is operated in the presence
of hydrogen with a molar ratio of hydrogen to chlorine of higher
than 5, at a temperature of between 25 and 350.degree. C. and at a
pressure of between 0.2 and 5 MPa.
6. A process for purification by elimination of chlorine according
to claim 1 wherein the two masses of the elimination zone are
either charged in the same reactor or in two different
reactors.
7. A process for purification by elimination of chlorine according
to claim 1 wherein when the second mass is saturated, said second
mass is discharged separately while diverting the effluent from the
reforming zone towards a third reactor comprising a hydrogen
chloride adsorbent.
8. A process for purification by elimination of chlorine according
to claim 1 wherein the hydrogen chloride adsorbent is an alumina
promoted with an alkali metal or an alkaline earth metal.
9. A process according to claim 1, wherein the mineral carrier
comprises alumina balls having a diameter of about 3 mm and a skin
thickness of palladium at about 300 microns.
10. A process according to claim 1 wherein said skin thickness is
on the order of about 10% of the diameter of the beads or
extrudates.
11. A process according to claim 1 wherein said mineral carrier is
impregnated with an aqueous or organic solution of a palladium
precursor.
12. A process according to claim 11 wherein the precursor is
palladium nitrate.
13. A process according to claim 12, wherein the mineral carrier
comprises alumina balls having a diameter of about 3 mm and a skin
thickness of palladium at about 300 microns.
Description
The present invention relates to a process for purification by
elimination of chlorine in the form of hydrogen chloride and
organochlorine compounds.
We are going to illustrate the present invention in the case of a
process for purification by elimination of chlorine on a part of an
effluent from a reforming zone.
One of the aims of catalytic reforming is to obtain hydrocarbons
having an increased octane number. It is established that the
octane number of a hydrocarbon is higher in proportion to an
increasing degree to which it is branched, cyclic and indeed
aromatic. In that way cyclisation and aromatisation reactions for
the hydrocarbons will be promoted.
Usually such hydrocarbon cyclisation and aromatisation reactions
take place in the presence of chlorinated bimetallic heterogeneous
catalysts. Those chlorinated catalysts are alumina-based and most
frequently comprise platinum and another metal such as for example
tin, rhenium or iridium. The presence of chlorine in such catalysts
is important as, added to the alumina, it ensures overall acidity
for the system and participates in redispersion of the platinum in
the course of time, thus making it possible to stabilise the
catalytic activity of the catalyst.
The addition of chlorine however is not a solution without its
disadvantages. In fact, with the passage of time, it is found that
there is elution of the chlorine, in particular in the form of
hydrogen chloride. Such elution is manifested firstly by the
constant necessity to replenish the catalyst with chlorine. It also
leads to the presence of hydrogen chloride and other chlorine
compounds in the gaseous and liquid effluents issuing from the
catalytic reforming operation, which can result in a problem in
terms of corrosion of the installation, a problem regarding the
formation of deposits or salts based on chlorine or a problem in
regard to accelerated contamination of the catalysts disposed
downstream, for example benzene hydrogenation catalysts.
Catalytic reforming also produces hydrogen. In refining petroleum
hydrogen is a particularly precious product, in particular by
virtue of its use in hydrotreatments which are being increasingly
developed with the aim of improving environmental protection.
As the discharge from traditional catalytic reforming which
operates under a pressure of about 2 MPa or indeed above, the
gaseous effluents are for the major part composed of hydrogen,
light hydrocarbons such as methane, ethane . . . , and in general
have traces of hydrogen chloride and water. It is therefore
important to be able to remove all traces of hydrogen chloride from
such effluents, for example on alumina-based solids, and then
recycle and therefore use the purified hydrogen, still in a
refinery situation.
Moreover, regenerative or regeneration processes have recently been
devised and are being increasingly developed on the ground. Those
processes operate under a pressure of close to 0.3 to 1.5 MPa, or
even less.
As the discharge from a regenerative catalytic reforming operation,
in addition to hydrogen, light hydrocarbons, traces of hydrogen
chloride and water, traces of unsaturated hydrocarbons such as
ethylene, propylene, butenes, butadiene . . . have been detected.
Those unsaturated hydrocarbons, in the presence of chlorine and in
contact with adsorbent, are at least partially transformed into
organochlorine compounds which are precursors of oligomers of high
molecular masses. Those `green oils` can give rise to blockages in
the installation. Hence, a significant reduction in the service
life of the adsorbent is found: in certain cases a reduction of 4
to 5 times has been observed.
That phenomenon is also observed in relation to alumina-based
solids dedicated to the removal of chlorine in liquid effluents
from catalytic reforming which do not entirely eliminate the
organochlorine compounds present and in addition can result in the
formation of organochlorine compounds in the presence of
monoolefins/diolefins and hydrogen chloride.
The aim of the present invention is to propose an improved process
for effective elimination of chlorine compounds and hydrogen
chloride, more particularly, contained in a gas or a liquid.
Another aim of the present invention is to propose a process
employing a composition which will substantially reduce or indeed
suppress the formation of oligomers and in particular chlorinated
oligomers referred to as `green oils`, downstream of the
regenerative or regeneration reforming processes.
An attraction of the present invention is that suppression of the
chlorine compounds makes it possible in particular to avoid the
harmful formation of NH.sub.4Cl and corrosion problems linked to
the chlorine.
Another attraction of the present invention is that the suppression
of the chlorine compounds makes it possible to protect the
catalysts of the downstream units, in particular the catalyst of
the benzene hydrogenation unit.
PRIOR ART
Patent application EP 1053053 describes a process for eliminating,
reducing and/or suppressing halogen compounds contained in a gas or
a liquid, wherein the gas or the liquid is brought into contact
with a composition obtained by deposit on an alumina of at least
one compound comprising at least one element selected from alkali
metals, followed after the deposit operation by calcination of the
alumina at a temperature of at least 600.degree. C.
Patent application EP 0948995 describes a process for eliminating
the halogen compounds contained in a gas or a liquid wherein the
gas or the liquid is brought into contact with a composition
comprising an alumina and/or a hydrated alumina and at least one
metallic element selected from the group formed by the metals of
groups VIII, IB and/or IIB.
SUMMARY OF THE INVENTION
The invention concerns a process for purification by elimination of
chlorine in the form of hydrogen chloride and organochlorine
compounds by contacting in the presence of hydrogen of at least a
part of the effluent from a reforming, aromatics production,
dehydrogenation, isomerisation or hydrogenation zone, said part of
the effluent comprising olefins, hydrogen chloride and
organochlorine compounds, on an elimination zone comprising a chain
arrangement of two masses, the first mass being a mass comprising
at least one metal from group VIII deposited on a mineral carrier
and the second mass being a hydrogen chloride adsorbent.
DETAILED DESCRIPTION OF THE INVENTION
In the text group VIII corresponds to group VIII in accordance with
the classification CAS corresponds to the metals of columns 8 to 10
in accordance with the new IUPAC classification (CRC Handbook of
Chemistry and Physics, publisher CRC Press, editor D R Lide, 81st
edition, 2000-2001.
In the context of this patent application the term olefin
corresponds to monoolefins and/or diolefins.
The invention concerns a process for purification by elimination of
chlorine in the form of hydrogen chloride and organochlorine
compounds by contacting in the presence of hydrogen of at least a
part of the effluent from a reforming, aromatics production,
dehydrogenation, isomerisation or hydrogenation zone, said part of
the effluent comprising olefins, hydrogen chloride and
organochlorine compounds, on an elimination zone comprising a chain
arrangement of two masses, the first mass being a mass comprising
at least one metal from group VIII deposited on a mineral carrier
and the second mass being a hydrogen chloride adsorbent.
In accordance with a preferred variant at least a part of the
effluent from the reforming zone circulates through a gas-liquid
separator, said separator leading to a flow of gas rich in hydrogen
(A) and a liquid effluent (B), said liquid effluent being passed to
a stabilisation zone, said stabilisation zone leading to at least
two cuts, a first light cut (C) and a first heavy cut (D), said
first heavy cut being passed to a fractionating column leading to
the production of at least two cuts, a second light cut (E1) taken
off at the column head, optionally a cut (E2) taken off between the
column head and the supply for the column, each of which cuts (E1)
and (E2) can be passed to a benzene hydrogenation zone, and a
second heavy cut (F). The purification zone is placed on any flow
coming from the gas-liquid separator, the stabilisation column or
the fractionating column.
In accordance with a preferred variant of the invention the
purification zone is placed on the flow of gas which is rich in
hydrogen (A), the liquid effluent (B) or at least one of the cuts
(E1) or (E2).
In accordance with a variant hydrogen is added in the contacting
operation on the elimination zone of at least a part of the
effluent from a reforming, aromatics production, dehydrogenation,
isomerisation or hydrogenation zone.
The two masses of the collection zone are generally either charged
in the same reactor or in two different reactors. In the case where
the two masses are charged in the same reactor the first mass is
generally the catalytic mass and the second mass is generally the
hydrogen chloride adsorbent.
In accordance with a variant the two masses are disposed in the
same reactor and the first mass is generally disposed at the head
of the collection zone. It then occupies a volume generally
corresponding to 10 to 60% of the total volume of said zone.
In accordance with a variant when the second mass is saturated it
is discharged separately while diverting the charge to be treated
towards a third reactor comprising a hydrogen chloride adsorbent.
That makes it possible to ensure continuity in the operation.
The metal from group VIII which is selected will preferably be
palladium and/or platinum. Those metals are deposited on the
carrier using methods which are known to the man skilled in the
art, namely by impregnation with aqueous solutions of soluble
palladium and platinum salts. For example, if the metal from group
VIII is palladium, it can be introduced by procedures involving
impregnation with an aqueous or organic solution of a palladium
precursor. That precursor may be for example a mineral compound
such as palladium chloride, palladium nitrate, tetramine palladium
dihydroxide, tetramine palladium chloride or an organometallic
compound such as for example palladium his z-allyl or palladium
bis-acetylacetonate. The palladium is deposited preferably in a
skin configuration, that is to say at the surface of the catalyst
grains, for example balls or cylindrical extrudates, with
penetration into the grains which is comprised in a peripheral
layer not exceeding for example 80% of the radius of the balls or
cylinders. The skin thickness is generally between 100 and 700
micrometres.
After introduction of the different elements the catalyst is
generally dried at about 120.degree. C. and then calcined at
temperatures generally between 150 and 700.degree. C.
The palladium or platinum content is generally between 0.1 and 1%
by weight and preferably between 0.2 and 0.6% by weight.
The mineral carrier used can be selected from alumina, silica,
silica alumina, silica magnesia, titanium oxide, aluminosilicates
of zeolites type, all those solids being used alone or in a mixture
with each other. Preferably alumina will be used.
The second mass can be selected from all those known for
effectively adsorbing hydrogen chloride. They can be formed by one
or more alkali metal or alkaline earth metal compounds deposited on
an alumina of a specific surface area which is generally between 50
and 400 m.sup.2/g.
They may also comprise mixed oxides, in particular based on copper
and/or zinc.
The content of alkali metal or alkaline earth metal is generally
between 0.5% and 70% by weight and preferably between 2% and 35% by
weight with respect to the total weight of the composition.
Deposit of the alkali metal and alkaline earth metal elements can
be effected by any method known to the man skilled in the art, for
example by impregnation of the alumina with an aqueous solution of
soluble alkali metal or alkaline earth metal salts. After
impregnation the mass is dried and calcined in suitable fashion,
the calcination temperature generally being between 300 and
900.degree. C.
The second mass can be in any form permitting the highest level of
accessibility and thus the greatest possible capacity for
adsorption of hydrogen chloride. For example use will be made of
balls or extrudates which can be of any shapes, for example in the
form of trilobates. The mean diameter of the balls and extrudates
will be the smallest possible, for example between 1 and 5 mm,
while taking care not to cause excessively great pressure drops in
the reactor.
The part of the effluent from the reforming zone which is treated
generally contains between 0.1 and 50 ppm by weight of chlorinated
compounds reckoned as chlorine. In general the elimination zone is
operated in the presence of hydrogen, preferably with a molar ratio
of hydrogen to chlorine of higher than 5, very preferably with a
molar ratio of hydrogen to chlorine of between 5 and 10.sup.6, at a
temperature of between 25 and 350.degree. C., preferably between 35
and 200.degree. C., preferably between 130 and 180.degree. C., and
at a pressure of between 0.2 and 5 MPa, preferably between 0.5 and
4 MPa, preferably between 1 and 3 MPa.
The space velocities of the gases to be purified, expressed as an
hourly flow rate by volume TPN of the gas divided by the mass
volume, GHSV, are generally between 50 and 2000 h.sup.-1 and
preferably between 100 and 1000 h.sup.-1.
The space velocities of the liquids to be purified expressed as an
hourly flow rate by volume of liquid divided by the mass volume
(LHSV) are generally between 1 and 50 and preferably between 2 and
40 h.sup.-1.
The hydrogen may be initially present in the hydrocarbon charge to
be treated. In particular in liquid charges in dissolved form from
100 molar ppm. The hydrogen can also be added in the contacting
operation in the elimination zone in respect of at least a part of
the effluent from a reforming, aromatics production,
dehydrogenation, isomerisation or hydrogenation zone.
FIG. 1 shows treatment of the effluent from the reforming zone.
At least a part of the effluent from the reforming zone circulates
by way of the line 1 through a gas-liquid separator 10, the
separator resulting in a flow of gas which is rich in hydrogen A
flowing by way of the line 2, and a liquid effluent B flowing by
way of the line 3, the liquid effluent being passed by way of the
line 3 to a stabilisation zone 11, the stabilisation zone leading
to at least two cuts, a first light cut C flowing by way of the
line 4 and a first heavy cut D flowing by way of the line 5, the
first heavy cut being passed by way of the line 5 to a
fractionating column 12 leading to the production of at least two
cuts, a second light cut E1 which is taken off at the column head
and flows by way of the line 6, optionally a cut E2 which is taken
off between the column head and the supply for the column and flows
by way of the line 7, each of which cuts E1 and E2 can be passed to
a benzene hydrogenation zone, and a second heavy cut F flowing by
way of the line 8. The purification zone is placed on any flow from
the gas-liquid separator 10, the stabilisation column 11 or the
fractionating column 12.
EXAMPLE 1
Comparative
This procedure uses an alumina prepared in accordance with the
preparation method described in patent application EP 1053053. It
is in the form of balls measuring 2 to 5 mm and is of a specific
surface area of 349 m.sup.2/g. Sodium is firstly incorporated by
what is referred to as dry impregnation of a solution of NaNO.sub.3
so as to produce 6.7% by weight of sodium after drying at
100.degree. C. and calcination at 820.degree. C.
100 cm.sup.3 of that mass A is placed in a cylindrical reactor and
the reactor is supplied with a liquid effluent (high-severity
reformate) coming from a gas-liquid separator of the reforming
unit. That effluent is referred to as B in the description.
The characteristics of that high-severity reformate are as
follows:
TABLE-US-00001 ASTM distillation initial point: 20.degree. C. final
point: 200.degree. C. Content of monoolefins: 1.9% by weight
Content of diolefins: 1000 ppm by weight Content of H2: 0.15% mole
Content of chlorine (ex HCl): 6 ppm by weight (1) Content of
chlorine (ex organochlorines): 2 ppm by weight (2) (1) analysis
method: UOP 588 (2) analysis method: ASTM D 4929
That reformate is circulated at a flow rate of 2 litres per hour,
which corresponds to a liquid space velocity of 20 h.sup.-1. The
reactor is operated at a temperature of 140.degree. C. and under a
pressure of 1 MPa.
That reactor is operated for a period of 1000 hours.
The contents of olefins and chlorine at the end of 200 hours and
1000 hours are measured.
The results obtained are summarised in the following table:
TABLE-US-00002 Concentrations After 200 hours After 1000 hours
Chlorine ex HCl (ppm by weight) 0 1 Chlorine ex organochlorines 2 7
(ppm by weight)
It is noted that only the HCl is absorbed by the mass at the end of
200 hours. In contrast, at the end of 1000 hours, the appearance of
a substantial concentration of organochlorines is noted, the HCl
itself no longer being totally absorbed. That is explained by the
fact that the mass is saturated by the HCl and that the latter,
instead of being adsorbed, reacts with the olefins present to form
organochlorine compounds.
EXAMPLE 2
According to the Invention
A mass B comprising 0.3% by weight of palladium deposited on
alumina is prepared. The palladium is deposited by what is referred
to as dry impregnation from Pd(NO.sub.3).sub.2. The alumina is in
the form of balls measuring 3 mm in mean diameter, it is of a
specific surface area of 120 m.sup.2/g. After impregnation the mass
is dried at 120.degree. C. and then calcined at 450.degree. C. The
result obtained is a deposit of palladium which remains in skin
form on the ball. The thickness of that skin is 300 microns.
A second mass C is prepared using the preparation method described
in patent application EP 1053053 comprising 6.7% of Na after
impregnation of NaNO.sub.3 and calcination at 820.degree. C. of an
alumina equivalent to that described in Example 1.
100 cm.sup.3 of each of those masses is placed in a cylindrical
reactor, the first at the head, the second at the bottom, the two
being separated by a metal grid.
Operation is implemented with the same liquid charge and under the
same conditions as those in Example 1. That reactor is operated for
a period of 1000 hours and the contents of olefins and chlorine are
measured at the end of 200 hours, 800 hours and 1000 hours.
The results obtained are summarised in the following Table:
TABLE-US-00003 After 200 After 800 After 1000 Concentrations hours
hours hours Chlorine ex HCl (ppm by weight) 0 1 8 Chlorine ex
organochlorines 0 0 0 (ppm by weight)
It is observed that all the organochlorines are transformed. The
first trace of HCl however appears at the end of 800 hours, which
announces approaching saturation of the HCl collection mass.
EXAMPLE 3
According to the Invention
This Example involves treating the light cut (referred to as the
light reformate and containing the major part of the benzene)
issuing from the fractionating column prior to being passed to a
benzene hydrogenation zone. That cut is referred to as E1 in the
description.
The characteristics of that cut are as follows:
TABLE-US-00004 ASTM distillation initial point: 35.degree. C. final
point: 75.degree. C. Content of monoolefins: 1.0% by weight Content
of diolefins: 1000 ppm by weight Content of chlorine (ex HCl): 2
ppm by weight (1) Content of chlorine (ex organochlorines): 1.5 ppm
by weight (2)
100 cm.sup.3 of the palladium catalytic mass B as described in
Example 2 is disposed in a first reactor.
100 cm.sup.3 of the HCl collection mass C of Example 2 is charged
in a second reactor.
A flow rate of 1 litre per hour of the charge to be treated is
passed over those two reactors disposed in series, under the
following conditions: Temperature: 140.degree. C. Pressure: 2.5 MPa
H.sub.2 flow rate: 240 litres TPN/hour (that is to say about 1 mole
H.sub.2/mole of charge).
The two reactors are operated for a period of 1000 hours and the
contents of olefins and chlorine at the end of 500 and 1000 hours
are measured.
The results obtained are summarised in the following table:
TABLE-US-00005 Concentrations After 500 hours After 1000 hours
Olefins (% by weight) 0.1 0.1 Chlorine ex HCl (ppm by weight) 0 0
Chlorine ex organochlorines (ppm by 0 0 weight)
It is noted that all the chlorine compounds are totally
eliminated.
EXAMPLE 4
According to the Invention
This time the gaseous effluent rich in hydrogen (referred to as A
in the description) from the separator of the reforming unit is
treated, the composition thereof being as follows:
TABLE-US-00006 Composition % mole H.sub.2 92 C.sub.1 1 C.sub.2 1.2
.sub. C.sub.3+ 1.3 .sub. C.sub.4+ 4.5 Olefins 0.1
Analysis of the chlorine compounds:
TABLE-US-00007 HCl 3 ppm vol Organochlorines 0
This Example 4 involves comparing the behaviour of the mass A with
that of the combination of masses B and C.
One case involves using the reactor which is charged as in Example
1 while the other case involves using the arrangement of Example
2.
Operation is implemented under the following conditions: Pressure:
1.5 MPa T.degree. C.: 40.degree. C. Gaseous flow rate: 80 litres/h
(GHSV=800 h.sup.-1)
The results obtained after 200 hours and 1000 hours are summarised
in the following table:
TABLE-US-00008 After 200 hours After 1000 hours Concentrations
Arrangement Arrangement Masses A B + C A B + C Olefins (ppm vol)
500 <10 500 <10 Chlorine ex HCl (ppm vol) 0 0 0.5 0.3
Chlorine ex organochlorines 0 0 2.5 0 (ppm vol)
It is observed that the mass A of Example 1, at the end of 1000
hours, causes disappearance of the HCl not by adsorption but by
addition to the olefins present. In contrast, the arrangement of
Example 2 with the masses B and C continues to eliminate the HCl
virtually totally, avoiding the formation of organochlorines by
virtue of virtually complete hydrogenation of the olefins
present.
* * * * *